package thread.test7AQS.SelfLock;

import java.util.HashMap;
import java.util.Map;

public class ClientTest {
    public static void main(String[] args) {
        Map map=new HashMap();
        map.put(1,2);
        map.put(null,3);
        System.out.println(map.get(1));
        System.out.println(map.get(null));
    }
}
